The present technology relates to a zoom lens and an imaging apparatus. The zoom lens has a configuration of five groups which are arranged to have positive, negative, positive, negative, and negative refractive powers in order from the object side to the image side.
In known methods in the past, an imaging device using a photoelectric conversion element such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) is used as recording means in an imaging apparatus such as a camera, and a subject image, which is formed on a surface of the imaging device, is converted into an electrical output by the photoelectric conversion elements, and is recorded.
Further, in accordance with advancement in a recent microfabrication technology, a speed of a central processing unit (CPU) increases, high integration of a storage medium advances, and thus it is possible to process a large volume of image data at a high speed. Meanwhile, even a light receiving element is also reduced in size and more highly integrated, and is thus able to perform recording of a higher spatial frequency. In accordance with reduction in size, it is possible to reduce a size of the entirety of a camera.
In contrast, recently, an imaging apparatus, which has no mirror box in a camera main body, referred to as a mirrorless camera system that has spread remarkably, normally employs a short flange back with a width larger than that of the existing single-lens reflex camera system. Thus, the camera main body is designed to have a smaller size.
Due to such a background, for an interchangeable lens of a recent interchangeable lens digital camera system, there is a high demand to achieve high imaging performance according to a high spatial frequency of the light receiving element, and there is a high demand to reduce the size of a lens according to reduction in the size of the camera.
In the recent interchangeable lens digital camera system, there is a demand for a lightweight focus lens group capable of capturing a moving image and performing focusing at a high speed appropriate for tracking of a subject during the capturing of the moving image.
A recent zoom lens used in the interchangeable lens of the interchangeable lens camera is mostly a zoom lens using multiple lens groups in which three or more lens groups are movable. Generally, the zoom lens using multiple lens groups has a high degree of freedom of the change in the relative position caused by zooming of the lens groups, and it is advantageous to correct aberrations. Further, by distributing the zooming operation among the lens groups, the zoom lens also has an advantage in that it is easy to achieve an increase in the magnification and minimize the shift lengths of the lens groups during zooming.
Examples of the zoom lens using multiple lens groups include zoom lenses having a configuration of five groups described in Japanese Unexamined Patent Application Publication No. 2009-175324 and Japanese Unexamined Patent Application Publication No. 2009-244445.
The zoom lenses described in Japanese Unexamined Patent Application Publication No. 2009-175324 and Japanese Unexamined Patent Application Publication No. 2009-244445 include, in order from the object side to the image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; a third lens group that has a positive refractive power; a fourth lens group that has a negative refractive power; and a fifth lens group that has a positive refractive power.